Assembly and process for creating an extruded pipe for use in a geothermal heat recovery operation

ABSTRACT

An assembly and process for forming a two stage extruded pipe having a central inner sleeve and a pair of outer attached lobes. The central sleeve shaped (also termed a grout receiving tube) is produced in an initial extrusion operation, following which it enters a cross head operation where a pair of outer lobes are attached to cross sectional exterior surface locations according to a second stage extrusion operation so as to be integrally formed therewith. Other steps include cooling of the dual stage extruded pipe, as well as sectioning and stacking the pipe. Additional steps include forming elongated slots or apertures into the central sleeve portion of the finished extrusion, such in non-interfering fashion with the individual passageway defining and lobes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation-in-part of application Ser. No.13/726,771 filed on Dec. 26, 2012. Application Ser. No. 13/726,771claims the benefit of U.S. Provisional Application 61/586,464 filed onJan. 13, 2012, the contents of which are incorporated herein in theirentirety.

FIELD OF THE INVENTION

The present invention discloses both an assembly and process forsequential two stage extrusion of a geothermal pipe from a plasticizedmaterial, such as including but not limited to HDPE (high densitypolyethylene) pipe.

BACKGROUND OF THE RELEVANT ART

Geothermal heat recovery operations (also termed as a geothermal heatpump or ground source heat pump) are known in the art and which canprovide for either of heating or cooling by pumping heat to or from asubterranean zone beneath a ground surface and by which the relevantassembly employed uses the earth as a heat source (in the winter) or aheat sink (in the summer). In application, geothermal systems aredesigned to take advantage of the moderate temperatures in the ground toboost efficiency and reduce the operational costs of heating and coolingsystems. Ground source heat pumps are also known as “geothermal heatpumps” although, strictly, the heat does not come from the centre of theEarth, but from the Sun. They are also known by other names, includinggeoexchange, earth-coupled, earth energy systems.

Depending on latitude, the temperature beneath the upper 6 metres (20ft) of Earth's surface maintains a nearly constant temperature between10 and 16° C. (50 and 60° F.), if the temperature is undisturbed by thepresence of a heat pump. Like a refrigerator or air conditioner, thesesystems use a heat pump to force the transfer of heat from the ground.Heat pumps can transfer heat from a cool space to a warm space, againstthe natural direction of flow, or they can enhance the natural flow ofheat from a warm area to a cool one.

The core of the heat pump is a loop of refrigerant pumped through avaporcompression refrigeration cycle that moves heat. Seasonalvariations drop off with depth and disappear below 7 meters (23 ft) dueto thermal inertia. Like a cave, the shallow ground temperature iswarmer than the air above during the winter and cooler than the air inthe summer. A ground source heat pump extracts ground heat in the winter(for heating) and transfers heat back into the ground in the summer (forcooling). Some systems are designed to operate in one mode only, heatingor cooling, depending on climate.

SUMMARY OF THE INVENTION

The present invention discloses both an assembly and process forsequential two stage extrusion of a geothermal pipe from a plasticizedmaterial, such as including but not limited to HDPE (high densitypolyethylene) pipe. A central sleeve shaped and grout receiving tube isproduced in an initial extrusion operation. The central sleeve is shapedand cooled, following which it enters a cross head operation where apair of outer lobes are attached to exterior surface locations of thecentral sleeve according to a secondary extrusion operation so as to beintegrally formed therewith. Other steps include linearly drawing andany of spray, immersion or other types of cooling of the dual stage orco-extruded pipe, as well as sectioning and stacking the pipe.Additional steps include forming elongated slots or apertures into thecentral sleeve portion of the finished coextrusion in non-interferingfashion with the second arcuate shaped lobes.

Each of guide shape retention, cold-water spray or immersion hardening,cutting and cross drilling steps are provided for creating a pluralityof individual sections which are on site assembleable, such as utilizinghot plate welding technique. Additional top and bottom affixed caps areaffixed to ends of the elongate assembled piping and, upon embedding theassembly within a ground location in interfacing fashion with ageothermal environment, provide for temperature alteration of the innercommunicated fluid flow prior to delivery to a suitable piece of heatexpansion and energy transfer equipment, such as for creatingelectricity.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the attached drawings, when read incombination with the following detailed description, wherein likereference numerals refer to like parts throughout the several views, andin which:

FIG. 1 is plan schematic of the overall assembly and process accordingto the present invention;

FIG. 2 is a perspective illustration of the first stage extruder forforming the central sleeve;

FIG. 3 is an illustration of a vacuum chamber through which the centralsleeve passes after exiting the central sleeve extruder, an arrangementof upper and lower rollers communicating with the central sleeve at anoutlet of the vacuum chamber for imparting a cross sectional profile,such in order to compensate for heat induced deformation of the sleeveduring the subsequent crosshead die operation for extrusion forming thelobes upon exterior locations of the central sleeve;

FIG. 4 is an illustration of an interior of the vacuum chamber of FIG. 3and which depicts a plurality of progressing sizing dies for maintainingthe central sleeve in its proper shape during cooling thereof;

FIG. 5 is a succeeding secondary cooling tank operation for furthercooling the central sleeve utilizing a water spray;

FIG. 6 is a first overhead perspective illustration of a cross head dieoperation following the second cooling tank, the cross head dieincluding a pair of spaced and elongated mandrels between whichtraverses the central sleeve to facilitate the second extrusion formingthe outer lobes;

FIG. 7 is a rotated perspective of FIG. 6 and illustrating a pluralityof cooling lines communicating to the cross head die and interiorpassageways formed into each of the elongated lobe forming mandrels fortemperature control during the forming and attaching of the secondextruded lobes to the previously extruded central sleeve;

FIG. 8 is a back side perspective of the cross head die and stand andillustrating the arrangement of the inlet feed of coextruded andflowable material to the reverse side extending mandrels, as well as theplurality of coolant lines extending from the thermocouple controlledsub-assemblies for controlling the temperature profiles of the mandrels;

FIG. 9 is a side-by-side perspective of the coolant supply units alsodepicted in FIG. 8 and associated with the coolant lines andthermos-electric coupling devices extending to each lobe formingmandrel;

FIG. 10 is an end perspective of the forming mandrels extending from thedie head into the cooling and final shaping tank and which transitionthe outer formed lobes and inner central sleeve to pairs of guidingspindles arranged linearly spaced fashion along the cooling and formingtank;

FIGS. 10A and 10B are a pair of rotated and downward looking perspectiveviews of the cooling and shaping tank of FIG. 10 and furtherillustrating the coolant apertures pathways formed within the elongatedmandrels, as well as showing the pairs of spaced apart guiding spindlesfor assisting in transitioning the two stage extruded pipe from the lobeforming mandrels;

FIG. 11 is a further illustration of the cooling and shaping tank ofFIG. 10A, again illustrating spray nozzles without the pairs of guidingspindles;

FIG. 12 is a puller assembly for assisting in drawing of the dual stageextruded pipe and which precedes a press for sectioning the finishedpipe into predetermined lengths; and

FIG. 13 is a router station for configuring any type of aperture or slotshaped channel within the exposed linear extending portion of thecentral sleeve, such as for facilitating grout outflow during in groundinstallation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As previously described, the present invention discloses a processincorporating a sequential two stage extrusion process for creating suchas a polymeric type pipe which can be utilized in a geothermal fluidflow application. In one non-limited application, an HDPE (high densitypolyethylene) material is employed, such as which is fed in pelletized,granulated or other flowable form to in-feed hoppers associated witheach of a first or main extruder and a second stage extruder in order tocreate the two stage extruded pipe construction.

It is further envisioned that other material constructions can beemployed in the multi-stage extrusion process and in order to create aplurality of interconnecting pipe sections which are suitable forcommunicating a steady fluid (e.g. water, water based refrigerant orother suitable thermal conveying fluid) downwardly and successivelyupwardly along the running length of the embedded pipe and in order totake advantage of the geothermal gradient existing at certain locationsfor modifying a feed temperature of the fluid. In practice, the fluid istypically warmed (or cooled in the instance of a hot fed water input) toa general temperature range of 57° F., consistent with a typicalgeothermal gradient occurring within the earth crust and, upon beingrecovered from an outflow location of the uppermost pipe section, isusually fed into a fluid transfer/heat expansion mechanism forrecovering a work output (e.g. electricity).

Referring to FIG. 1, an overall schematic of the overall assembly andprocess is shown according to one non-limiting embodiment of the presentinventions, these being further described in detail with additionalreference to succeeding FIGS. 2-11, as well as additional post extrudingand sectioning/routing stations set forth in FIGS. 12 and 13respectively. A feed hopper assembly 10 contains a volume of extrudatematerial (again such as including but not limited to HDPE which can bein pellet or granulate four) and which is fed into a first or mainextruder 12 via a feed line 14.

An extrusion die (also termed as any of a forming head or first mandrel)is shown at 16 associated with the first extruder 12 (see also FIG. 2)and which is heated and temperature controlled as known in the art inorder to extrude a first sleeve shaped component 2 of the pipe (suchalso termed a main tube or central sleeve) in a first extrusionoperation. As again shown in FIG. 2, a known arrangement of heatingelements, thermo-electric coupling devices and other controls areprovided in order to extrude the first sleeve shaped component 2 througha disk shaped template configured within the forming head 16, suchexhibiting a desired wall thickness and dimensions.

A vacuum chamber 18, which is depicted as having a generally threedimensional and rectangular shape, is provided in communication with anoutlet of the first extruder 12 and for receiving the first sleeveshaped component 2. As further shown in FIG. 3, the vacuum chamber 18includes a hinged lid 20 which, upon opening, reveals a plurality ofdisk shaped forming dies 22, 24, 26 arranged in linearly spaced fashionbetween inlet 28 and outlet 30 ends of the chamber 18.

The vacuum chamber 18 operates create a desired negative pressure withinits interior (see extending fixture 32 and air evacuation passageway 34in FIG. 4) this in order to maintain the sleeve shaped component 2 inits proper shape while it cools. Located an exterior of the chamber 18,in intercepting proximity to its outlet 30, are upper 36 and lower 38and 40 spaced apart rollers, these further being rotatably supportedupon a vertical shelf or bracket 42. The sleeve shaped component 2, uponexiting the vacuum chamber 18, is intercepted between the lower rollers38/40 (such as shown in fixed rotational support with the shelf 42) andthe upper roller 36 which is both rotatably and pivotally supported alimited distance to a further bracket 44, in turn having an end pivotlocation 46 and an opposite (free end) abutment location 48, see furtherupper adjustable end stop 50 extending downwardly from the uppermost endof the shelf 42.

The purpose of the upper 36 and lower 38/40 spaced rollers is to flattenthe first sleeve shaped component at first 52 and second 54/56 crosssectional locations as it passes through the rollers and so that thecomponent acquires a modified cross sectional profile 2′. The purpose ofemploying the rollers and of imparting the offset/flattened shaping tothe profile 2′ has been found through trial and experimentation tocompensate for additional deformation experienced by the inner or sleeveshaped profile as it passes through the subsequent second extrusionstage crosshead die in proximity to the pair of elongated mandrelsduring the extruding of the exterior lobes. For purposes of the presentdescription, the use of the rollers 52 and 54/56 is optional (see againFIG. 4 which does not include a roller arrangement supported at anexterior outlet of the vacuum chamber 18) and it is further understoodthat other mechanisms are envisioned according to one of ordinary skillin the art for purposes of introducing an offset to the elongatedprofile 2 while it is still in a heated and formable shape.

Following exiting of the vacuum chamber 18 and passing through the shapeoffset upper roller 36 and lower rollers 38/40, (see arrow 58 in FIG.3), the now deformed single walled pipe 2′ is fed through a cooling tank60 (FIG. 5) for further cooling the pipe or central sleeve utilizing awater spray. To this end, a plurality of nozzles 62 are arranged ininward opposing fashion along each of the opposite length extendingsides of the cooling tank, with water (or other coolant fluid) beingcommunicated through lines (see at 64) which supply the plurality ofspray nozzles.

As further shown in FIG. 5, the cooling station 60 (optional) includesinlet 66 and outlet 68 ends through which the single walled pipe passes.Additional partitions 70 and 72 are defined at interior locations of thecooling station 60 and include additional aligning passageways (at 74and 76, respectively) through which pipe 2′ passes during cooling andsolidifying.

Referring again to FIG. 1, in combination with FIGS. 6-9, a second stageor co-extruder station 78 is located downstream of the main extruder 12and, in the illustrated embodiment, beyond the optional cooling tank 60.The second stage extruder 78 includes a cross head die 80 supported inelevated fashion upon a stand 82 and so as to be arranged in horizontalalignment with the single walled pipe.

A second extruded material is fed from the second stage extruder 78(such again including a melted and flowable HDPE or other suitableplastic) from a pipe or conduit (see at 84) in FIG. 8 to the cross headdie 80 and so that the extrudate material flows through an internaltemplate (not shown) defined within the cross die head. The secondextruder also includes a pair of elongated mandrels 86 and 88 (such aswhich are constructed of any aluminum or other suitable metal or likematerial) which extend from an outlet of the cross head die 80 andbetween which communicates the sleeve shaped component 2.

The mandrels 86 and 88 (see as also shown in succeeding FIGS. 10, 10Aand 10B) each exhibit an arcuate or other configured cross sectionalprofile. In the illustrated embodiment, the mandrels are configured soas to extrude a pair of kidney or lobe shaped profiles onto the exteriorof the previously extruded single walled pipe.

Although not clearly shown, the second extrudate material deliveredthrough the pipe 84 (and such as which can again without limitationinclude an HDPE or other previously melted or flowable material) iscommunicated to an interior of the die head 80 which in turn configuredto communicate the material via an inner profile or template such thatit flows over and around the cross sectional kidney shape of eachmandrel 86 and 88 for the extending length of the mandrels during whichthe second stage extruded lobes, see at 90 and 92 in end view of FIG.10, also conjoin with circumferentially spaced apart surface locationsof the previously extruded pipe 2, thereby forming a pair of individualpassageway defining lobes upon the sleeve.

The second extruder further includes independent temperature controlsfor each of the elongated mandrels 86 and 88, these assisting in shapingthe attachment interface between the lobes 90 and 92 and central sleeve2. The independent temperature controls for each of the elongatedmandrels 86 and 88 further include pluralities of fluid lines, see asbest shown in FIGS. 7 at 94, 96 and 98 for upper mandrel 86 and at 100,102 and 104 for lower mandrel 88, for communicating a coolant to aninterior of each of the mandrels 86 and 88, such as dictated by separatethermo-electric coupling devices in communication with the mandrels.

FIG. 8 is a back side perspective of the cross head die 80 and stand 82and illustrating the arrangement of the inlet feed of coextruded andflowable material to the reverse (back) side extending mandrels 86 and88, as well as the plurality of coolant lines 94-98 and 100-104extending from a pair of fluid generating sub-assemblies (see asrepresented at 106 and 108 which may include internal pumps or the likefor assisting in generating fluid flow through the mandrels) and forcontrolling the temperature profiles of the mandrels. A pair ofpassageway defining networks (see at 110 for upper mandrel 86 and at 112for lower mandrel 88) are provided along the extending interior of themandrels and to which the pluralities 94-98 and 100-104 of fluid linesare communicated, this in order to control the temperature of themandrels during the second stage extrusion process. Also shown in FIG. 8at 114 is a separate unit which may include any type of Thermalator® orthermo-electric coupling controls, these interfacing with the pumpcontrolled upper 106 and lower 108 coolant subassemblies and associatedvalve structure in communicating with the fluid lines 94-98 and 100-104in order to direct fluid through the interior of the mandrels 86 and 88.

In this manner, the surface temperatures of the mandrels 86 and 88 areindependently controlled so as to assist in shaping and smoothing theinner wall of each extruded lobe 90 and 92 of material as it is joinedabout the exterior perimeter of the previously extruded single walledpipe 2. At this point, the heat associated previous cross sectionaloffset 2′ or correction effectuated by the intercepting upper 36 andlower spaced apart 38 and 40 rollers into the cross sectional profile ofthe pipe is further deformed by the heat of the mandrels 86 and 88 inthe second stage extrusion process, such resulting in the creation of atwo stage extruded pipe in which the inner single walled componentreverts back to a substantially symmetrical and circular cross sectionalshape.

Although not clearly shown, it is also understood that the lineardimensions of the mandrels 86 and 88 can be tapered or otherwisemodified, such including an inward taper of 6% in one non-limitingvariant between the crosswise dimensions taken from the cross head die80 to the extending ends of the mandrels. The dimensioning of themandrels is intended to counter the natural phenomena effects of theHDPE extrudate material for the lobes as it is formed, conjoined andhardened to the exterior of the single walled pipe 2 and so that theresultant two stage extruded pipe exhibits consistent length and widthdimensional profiles.

The mandrels 86 and 88 extend from cross head die 80 and into aninterior of a cooling station 116. The cooling station 116 furtherincludes a plurality of linearly spaced apart pairs of supportingspindles see at 118/120, 122/124, 126/128 et seq., between whichtraverses the two stage extruded pipe. As further best shown in FIG.10B, the mandrels 86 and 88 extend between at least the first two pairsof spaced apart spindles 118/120 and 122/124 during the progressivesecond stage extrusion of lobes 90 and 92 on the single walled pipe 2.

The pairs of spindles each exhibit a modified spool shape, see as bestshown in end view of FIG. 10, with each including a pair of upper130/132 and lower 134/136 arcuate surfaces separated at an intermediateheight by an annular ledge 138 and 140. The shaping of the spindles issuch that the extruded profile of the upper/lower lobes 90 and 92 formedby the mandrels 86 and 88 ride between the upper and lower arcuateopposing surfaces of the pairs of spindles, with the cross sectionalseparation between the lobes and the central pipe 2 seating between thelikewise opposing intermediate ledge of each spindle.

The construction of the spindles, such including a metallic or anysuitable supporting material, is also such that the spindles are capableof being inter-displaceable in at least one of first x 142 and second y144 axes in response to contact with the pipe as it is displacedtherebetween. X axis displacement can be effectuated by rotatablysupporting the spindles upon vertical mounting posts 146 and 148, theseextending upwardly from a base interior surface 150 of the coolingstation 116 (likewise exhibited as an elongated three dimensionalrectangular shaped structure with a generally open interior and havingan inlet end 152 and an outlet end 154).

As further shown, a plurality of coil springs (see at 156, 158, 160 etseq.) equal in number to each respective pair of guiding spindles isprovided and each includes opposite curled ends which engage the upperends of each pair of vertical spindle support posts (again at 146 and148 in FIG. 10). The posts can be configured so that they are allowed anincremental degree of lateral give or displacement (along axis x 142) inresponse to incidental contact between the extruded pipe and thespindles, thereby allowing the spindles to flex laterally against thebiasing effect of the coil springs. As further clearly shown, y axis 144displacement of the spindles is further easily accomplished by theirvertical channel seating interiors (not shown but through which theposts extend) allowing the spindles to slide up and down along thevertical posts 146/148.

The cooling station 116 further includes pluralities of nozzles, see at162 and 164 and which are supported on opposite interior extending sidesof the station 116 via fluid supply lines 166 and 168 (these in turnconnected to remote coolant supply reservoirs) for supplying a spraycoolant to the two stage extruded pipe as it translates through thestation 116. As with the initial stage cooling station 60, spray coolantis collected at an interior drain basin within the station and recycledor drained as desired.

Following exiting from the cooling station 116, the completed two stageextruded pipe 170 is drawn through a puller 172 (FIG. 12) for sectioningat a subsequent operation 174 (also depicted by blade 174 in FIG. 12)the finished pipe into predetermined lengths. Finally, and referencingFIG. 13, a router station 176 or the like is provided (can be part of astand-alone arrangement apart from the operational schematic of FIG. 1)and which is configured to aperture or router any hole, slot/channel orother perforation within the exposed linear extending portion of thecentral sleeve 2, such as for facilitating grout outflow duringsubsequent in ground installation.

Without limitation, the sizing and shaping or cross sectionaldimensioning of the exterior lobes 90 and 92 are not limited to thatshown and in which the down/inflow lobe 90 exhibits a larger inner areain comparison to the up/outflow lobe 92, this in order to maintaindesired directional fluid flow as well as to optimize the thermodynamicsassociated with the geothermal conditioned fluid delivered to theassociated heat transfer (not shown) or other suitable output equipmentmounted in fluidic communication with the outflow lobe. It is alsoenvisioned that any suitable guide shape retention, cold-water immersionhardening, cutting and cross drilling steps may also disclosed forcreating a plurality of individual sections for ease of transport and onsite assembly, such as utilizing hot plate welding techniques forjoining previously sectioned lengths of finished pipe. Additional topand bottom affixed caps (not shown) are affixed to ends of the elongateassembled piping and, upon embedding the assembly within a groundlocation in interfacing fashion with a geothermal environment, provide acommunicating fluid flow both downward and return/upwardly withtemperature alteration of the inner communicated fluid flow prior todelivery to such as a suitable piece of heat expansion and energytransfer equipment, not limited to that previously described in thebackground description and, in one application, such as specifically forcreating electricity.

An associated process for creating a two stage extruded pipe is alsoprovided and includes the steps of extruding a first sleeve shaped andelongated component, and sizing the sleeve shaped component within achamber incorporating a series of linearly spaced sizing dies in orderto maintain a shape of the first sleeve shaped component during coolingthereof. Additional steps include extruding a pair of outer lobes toexterior surfaces of the sleeve shaped component at displacedcircumferential locations so that the lobes each define a separatepassageway and further so that the lobes do not contact one another,thereby revealing first and second exposed portions of the sleeve shapedcomponent. Other steps include cooling the two stage extruded pipe andsectioning the pipe into given lengths.

Other process steps drawn from the above assembly include inducing anegative pressure within the chamber, flattening first and second crosssectional locations of the sleeve shaped component prior to the step ofextruding the outer lobes, and cooling the sleeve shaped component priorto extruding the pair of outer lobes. Additional steps includeindependently controlling a temperature of each of the pair of elongatedlobe forming mandrels forming a portion of a crosshead die associatedwith the second stage extrusion, such including the use of coolant andthermos-electric coupling devices (or Thermalators®), and transitioningthe pipe from the elongated lobe forming mandrels to a plurality ofspaced apart pairs of supporting spindles during traversing of the pipethrough a second chamber downstream from the crosshead die. Finalprocess steps also include routing at least one exposed portion of thesleeve shaped component following the steps of extruding the outer lobesand cooling the two stage extruded pipe.

Having described our invention, other and additional preferredembodiments will become apparent to those skilled in the art to which itpertains, and without deviating from the scope of the appended claims.This can include such as combining the dies and patterns for creatingthe outer arcuate lobes into a single co-extruded die component, as wellas producing a co-extruded article in which the dies are reconfiguredfor producing a single lobe or other

We claim:
 1. A process for creating a two stage extruded pipe,comprising the steps of: extruding a first sleeve shaped and elongatedcomponent; sizing the sleeve shaped component within a chamberincorporating a series of linearly spaced sizing dies in order tomaintain a shape of the first sleeve shaped component during coolingthereof; extruding a pair of outer lobes to exterior surfaces of thesleeve shaped component at displaced circumferential locations so thatthe lobes each define a separate passageway and further so that thelobes do not contact one another, thereby revealing first and secondexposed portions of the sleeve shaped component; cooling the two stageextruded pipe; and sectioning the pipe into given lengths.
 2. Theprocess as described in claim 1, said step of sizing the sleeve shapecomponent further comprising inducing a negative pressure within thechamber.
 3. The process as described in claim 1, further comprising thestep of flattening first and second cross sectional locations of thesleeve shaped component prior to the step of extruding the outer lobes.4. The process as described in claim 1, further comprising the step ofcooling the sleeve shaped component prior to extruding the pair of outerlobes.
 5. The process as described in claim 1, said step of extrudingthe pair of outer lobes to exterior surfaces of the sleeve shapedcomponent further comprising the step of independently controlling atemperature of each of a pair of elongated lobe forming mandrels forminga portion of a crosshead die associated with the second stage extrusion.6. The process as described in claim 5, said step of controlling atemperature of each of the elongated lobe forming mandrels furthercomprising the step of communicating a coolant to an interior of each ofthe mandrels.
 7. The process as described in claim 5, said step ofcooling the two stage extruded pipe further comprising the step oftransitioning the pipe from the elongated lobe forming mandrels to aplurality of spaced apart pairs of supporting spindles during traversingof the pipe through a second chamber downstream from the crosshead die.8. The process as described in claim 1, further comprising the step ofaperturing at least one exposed portion of the sleeve shaped componentfollowing the steps of extruding the outer lobes and cooling the twostage extruded pipe.
 9. The process as described in claim 1, said stepof cooling the first sleeve shaped extruded component further comprisingspraying within a first cooling tank.
 10. The process as described inclaim 7, said step of cooling the second stage extruded pipe furthercomprising spraying the pipe in the second chamber.
 11. An assembly forproducing a two stage extruded pipe, comprising: a first extruderreceiving a first extrudate material for forming a sleeve shapedcomponent; a second extruder including a cross head die through which isfed the sleeve shape component, said second extruder also including apair of elongated mandrels extending from an outlet of said cross headdie and between which communicates the sleeve shaped component, a secondextrudate material flowing across each mandrel and conjoining the sleeveshaped component at circumferentially spaced apart locations in order toform a pair of individual passageway defining lobes upon the sleeve;said second extruder further having independent temperature controls foreach of said elongated mandrels and for assisting in shaping theattachment interface between the lobes and central sleeve; a coolingstation in communication with extending ends of said elongated mandrelsfor receiving and supporting the two stage extruded pipe during coolingand hardening; and a puller communicating with an outlet of said coolingstation for drawing the two stage extruded pipe and prior to cutting theco-extruded pipe to specified running lengths.
 12. The assembly asdescribed in claim 11, further comprising a vacuum chamber communicatingwith an outlet of said first extruder, a plurality of sizing dies beingarranged in linearly spaced fashion within said vacuum chamber andthrough which passes the sleeve-shaped component for maintaining a shapeof the component during cooling thereof.
 13. The assembly as describedin claim 12, further comprising a plurality of rollers supported at anoutlet end of said vacuum chamber and between which translates thesleeve-shaped component in order to flatten first and second crosssectional locations thereof.
 14. The assembly as described in claim 11,further comprising an HDPE pellet infeed hopper associated with saidfirst extruder.
 15. The assembly as described in claim 11, furthercomprising a secondary cooling station located between said first andsecond extruders, said secondary cooling station including a pluralityof nozzles for supplying a spray coolant to the sleeve shaped component.16. The assembly as described in claim 11, said independent temperaturecontrols for each of said elongated mandrels further comprising aplurality of fluid lines for communicating a coolant to an interior ofeach of the mandrels as dictate by separate thermo-electric couplingdevices in communication with said mandrels.
 17. The assembly asdescribed in claim 11, said cooling station further comprising aplurality of linearly spaced apart pairs of supporting spindles, betweenwhich traverses the two stage extruded pipe, said spindles beinginter-displaceable in at least one of first and second axes in responseto contact with the pipe.
 18. The assembly as described in claim 17,said cooling station further comprising a plurality of nozzles forsupplying a spray coolant to the two stage extruded pipe.
 19. Theassembly as described in claim 11, further comprising a post extrusionmachine for perforating at least one exposed portion of the sleeveshaped component of the two stage extruded pipe.
 20. An assembly forproducing a two stage extruded pipe, comprising: a first extruderreceiving a first extrudate material for forming a sleeve shapedcomponent; a vacuum chamber communicating with an outlet of said firstextruder, a plurality of sizing dies being arranged in linearly spacedfashion within said vacuum chamber and through which passes thesleeve-shaped component for maintaining a shape of the component duringcooling thereof, a plurality of rollers supported at an outlet end ofsaid vacuum chamber and between which translates the sleeve-shapedcomponent in order to flatten first and second cross sectional locationsthereof; a second extruder including a cross head die through which isfed the sleeve shape component, said second extruder also including apair of elongated mandrels extending from an outlet of said cross headdie and between which communicates the sleeve shaped component, a secondextrudate material flowing across each mandrel and conjoining the sleeveshaped component at circumferentially spaced apart locations in order toform a pair of individual passageway defining lobes upon the sleeve; acooling station in communication with extending ends of said elongatedmandrels for receiving and supporting the two stage extruded pipe duringcooling and hardening; and a puller communicating with an outlet of saidcooling station for drawing the two stage extruded pipe and prior tocutting the co-extruded pipe to specified running lengths.